1. Field of the Invention
The invention is in the field of injection devices. Specifically, the disclosure pertains to a medication pen adapted to deliver a mixture of separately dosed medications with a single injection.
2. Description of the Related Art
Medication pens are widely used for self-administered injectable drugs such as insulin. And patients are often required to take medications in combination with each other. For example, insulin is co-administered with glucagon like peptide (“GLP”). Therefore, it would be desirable if medications could be mixed at the time of use and co-administered with the convenience of a medication pen. The conventional thinking in the art is that a compact medication delivery device capable of mixing and delivering two medications with a pen needle would require a complicated valved manifold to keep the two medications from mixing.
U.S. Pat. No. 5,542,760, to Chanoch et al, incorporated by reference in its entirety, describes a syringe filler for mixing different types of insulin in a syringe. A syringe is inserted into a syringe holder assembly which is rotatably mounted on a housing for containing two medication cartridges. Using the syringe holder, the syringe may be aligned with either of the two medication cartridges. A separate dose is loaded into the syringe from each cartridge, thus avoiding the complications associated with free-mixing different types of insulin for diabetic patients who require different types of insulin.
The disadvantage of the device is that the syringe must be separately handled to conduct the filling process and the injection. Therefore, it would be desirable to have a pen-type device that can deliver mixtures of individually dosed medications.
U.S. Pat. No. 7,645,264, to Marsh et al., also incorporated by reference, discloses a medication pen having a collapsible secondary reservoir in addition to a primary reservoir (such as a cartridge). The secondary reservoir is used to provide a mechanical advantage when delivering medication to tissue layers encountering relatively high backpressure such as an intradermal space. Medication flows from the cartridge of a pen device to the axially aligned secondary reservoir in the pen needle with little or no backpressure. An injection is administered by collapsing the collapsible secondary reservoir and the delivery force of the injection is controlled by the relative sizes of the primary and secondary reservoirs. However, the pen-type device disclosed does not house more than one cartridge nor is the secondary reservoir used to mix different medications.
The present invention improves over the aforementioned prior art by providing an injection device having a pen needle assembly that can be installed on a housing containing a plurality of medication compartments, such that medications individually dosed from the plurality of medication compartments can be mixed in the pen needle assembly and delivered simultaneously.